JP7396353B2 - Map creation system, signal processing circuit, mobile object and map creation method - Google Patents

Description

The present disclosure relates to a map creation system, a signal processing circuit, a mobile object, and a map creation method for creating map data used for self-position estimation by a mobile object equipped with a laser range finder.

BACKGROUND ART The development of autonomously movable objects such as unmanned guided vehicles (unmanned guided vehicles) and mobile robots is progressing.

An autonomous mobile device having a scan point acquisition unit and a storage unit has been disclosed (for example, Japanese Patent Publication No. 2009-223900). The scan point acquisition unit scans the space ahead using electromagnetic waves or sound waves, receives reflected waves from planar obstacles such as walls, and acquires the position coordinates of the obstacles as scan points. As map information, a collection of line segments representing planar obstacles such as walls, fences, fences, etc. in the operating area is preset as map segments in the storage unit. The autonomous mobile device sets an area within a predetermined distance from the origin (the position of the scan point acquisition unit) in the area where the object coordinates can be measured by the scan point acquisition unit, depending on the operating environment.

The autonomous mobile device identifies the position of the planar obstacle on the map by comparing the scan segment obtained from the scan result within the area with the map segment. By reducing the number of scan points, the amount of computation of the self-location recognition unit can be reduced, thereby making it possible to make decisions for autonomous movement faster.

Japanese publication: Japanese Patent Application Publication No. 2009-223900

In order to accurately identify one's own location, it is preferable to improve the accuracy of the map.

Embodiments of the present disclosure provide a map creation system, a signal processing circuit, a mobile object, and a map creation method for creating a map, which solve the above problems.

In a non-limiting exemplary embodiment, the map creation system of the present disclosure is a map creation system that creates a map that a mobile object refers to in order to estimate its own position, the map creation system comprising: A laser beam is emitted while changing the angle, the reflected light is obtained, and the relationship between the emitted laser beam and the reflected light is used to calculate the distance to the reflection point existing within a measurable first distance for each angle. selecting one or more partial areas smaller than the measurable area from a measurable area defined by a laser range finder that acquires distance data indicating the distance, the first angular range and the first distance; and a signal processing circuit that creates a map using distance data indicating a distance to a reflection point included in the one or more partial areas, wherein the one or more partial areas are used by the mobile object to estimate its own position. It is narrower than the measurement area of the laser range finder used in the actual measurement.

In a non-limiting exemplary embodiment, the signal processing circuit of the present disclosure is a signal processing circuit used in a map creation system that creates a map that a mobile object refers to in order to estimate its own position, The production system has a laser range finder, and the laser range finder emits a laser beam while changing the angle within a first angle range, obtains reflected light, and combines the emitted laser beam and the reflected light. The signal processing circuit acquires distance data indicating the distance to a reflection point existing within a measurable first distance for each angle by using the relationship between the first angle range and the first measurable distance. A process of selecting one or more partial areas smaller than the measurable area from among the measurable area defined by the distance, and distance data indicating a distance to a reflection point included in the one or more partial areas. A process of creating a map using the mobile object is performed, and an area narrower than a measurement area of a laser range finder used when the mobile body estimates its own position is selected as the one or more partial areas.

In a non-limiting exemplary embodiment, a moving object of the present disclosure includes the signal processing circuit, the laser range finder, and a driving device for movement.

In a non-limiting exemplary embodiment, the map creation method of the present disclosure is a map creation method for creating a map that a mobile object refers to in order to estimate its own position, and the map creation method uses a laser range finder to A laser beam is emitted while changing the angle within one angle range to obtain reflected light, and by using the relationship between the emitted laser beam and the reflected light, the distance is within a first measurable distance for each angle. acquire distance data indicating a distance to a reflection point existing in select one or more partial areas narrower than a measurement area of a laser range finder used by the mobile object to estimate its own position, and indicate the distance to a reflection point included in the one or more partial areas; Create a map using distance data.

A further mapping system of the present disclosure, in a non-limiting exemplary embodiment, is a mapping system that creates a map for reference by a mobile object to estimate its own position, the mapping system comprising: an angle within a first angular range; emit a laser beam and obtain reflected light while changing the angle, and use the relationship between the emitted laser beam and the reflected light to reach a reflection point that exists within a measurable first distance for each angle. a laser range finder that acquires distance data indicating a distance, and one or more partial areas smaller than the measurable area from among the measurable area defined by the first angular range and the first distance. , and a signal processing circuit that creates a map using distance data indicating a distance to a reflection point included in the one or more partial areas.

According to the embodiment of the present disclosure, a map is created from scan data in which measurement errors of the laser range finder are suppressed, so it is possible to obtain a more accurate map. By using the map, the AGV can more accurately drive autonomously.

FIG. 1A is a diagram showing the configuration of an embodiment of a mobile object according to the present disclosure. FIG. 1B is a diagram showing the configuration of an embodiment of a map creation system according to the present disclosure. FIG. 2 is a diagram showing a plurality of laser beams (solid lines) emitted from the LRF 102 of the moving body 10 for each step angle. FIG. 3 is a diagram for explaining the detection error of the laser beam 15w having a spread. FIG. 4 is a diagram for explaining that the laser beam 15w having a spread increases the detection error. FIG. 5 is a diagram for explaining that an actually existing object G _real is detected as a larger object G _virtual . FIG. 6A is a plan layout diagram schematically showing the position of a moving body scanning a certain moving environment. FIG. 6B is a diagram showing a map (map M) of the environment 200 shown in FIG. 6A. FIG. 7 is a diagram showing the mobile body 10 and the measurable area SA of the mobile body 10. FIG. 8A is a diagram showing the relationship between the measurable area SA and the partial area SB used by the mobile object 10 when creating a map. FIG. 8B is a diagram showing the positional relationship between the moving body 10 and the object G when the moving body 10 moves and approaches the object G. FIG. 8C is a diagram showing the positional relationship between the moving body 10 and the object G when the moving body 10 moves further and approaches the object G. FIG. 9A is a diagram showing the measurable area SA of the mobile object 10 at the time of map creation. FIG. 9B is a diagram showing the positional relationship between the moving body 10 and the object G when the object G enters the measurable area SA. FIG. 9C is a diagram showing the exclusion region SV set in the measurable region SA and the selected partial regions SB-1 and SB-2. FIG. 9D is a diagram showing the positional relationship between the moving body 10 and the object G when the moving body 10 continues to move. FIG. 9E is a diagram showing the positional relationship between the moving body 10 and the object G when the intensity of the reflected light from the object G becomes equal to or less than the intensity threshold value _ITH . FIG. 10 is a diagram illustrating a map 204M created by arranging point groups acquired by the operations of the first example or the second example described above in the environment 200 in which the mobile object 10 moves. FIG. 11 is a diagram showing a process flow for creating a map with a limited measurement range. FIG. 12A is a diagram showing a first processing flow for selecting a partial area. FIG. 12B is a diagram showing a second processing flow for selecting a partial area. FIG. 13 is a list diagram for explaining the difference in measurement areas used by the mobile body 10 at the time of map creation and self-position estimation. FIG. 14 is a diagram showing an overview of a control system that controls travel of each AGV according to the present disclosure. FIG. 15 is a perspective view showing an example of an environment in which an AGV exists. FIG. 16 is a perspective view showing the AGV and tow truck before being connected. FIG. 17 is a perspective view showing the connected AGV and tow truck. FIG. 18 is an external view of an exemplary AGV according to this embodiment. FIG. 19A is a diagram illustrating a first example of the hardware configuration of the AGV. FIG. 19B is a diagram showing a second example of the hardware configuration of the AGV. FIG. 20 is a diagram showing an example of the hardware configuration of the traffic management device.

<Term>



The term "Automatic Guided Vehicle" (AGV) refers to a trackless vehicle that loads cargo manually or automatically, travels automatically to a designated location, and unloads the vehicle manually or automatically. "Automated guided vehicle" includes an unmanned tow vehicle and an unmanned forklift.

The term "unmanned" means that no human is required to steer the vehicle, and does not exclude that the automated guided vehicle transports "people (for example, those who load and unload cargo)."

An "unmanned towing vehicle" is a trackless vehicle that automatically travels to a designated location, towing a trolley that loads and unloads cargo manually or automatically.

An "unmanned forklift" is a trackless vehicle that is equipped with a mast that raises and lowers forks for transferring cargo, automatically transfers cargo onto the forks, automatically travels to a designated location, and performs automatic cargo handling operations.

A "trackless vehicle" is a vehicle that has wheels and an electric motor or engine that rotates the wheels.

A "mobile object" is a device that carries people or cargo and is equipped with a driving device such as wheels, a bipedal or multipedal walking device, a propeller, etc. that generates traction for movement. The term "mobile object" in this disclosure includes not only an automatic guided vehicle in a narrow sense, but also a mobile robot, a service robot, and a drone.

"Automatic driving" includes driving based on commands from a computer operation management system to which the automatic guided vehicle is connected via communication, and autonomous driving by a control device included in the automatic guided vehicle. Autonomous driving includes not only the movement of an automatic guided vehicle toward a destination along a predetermined route, but also the movement of the automated guided vehicle to follow a tracking target. Further, the automatic guided vehicle may temporarily perform manual travel based on instructions from a worker. "Automatic driving" generally includes both "guided" driving and "guideless" driving, but in this disclosure it means "guideless" driving.

The "guide type" is a method in which a guide is installed continuously or intermittently, and the guide is used to guide the automatic guided vehicle.

The "guideless type" is a method of guiding without installing a guide. The automatic guided vehicle in the embodiment of the present disclosure is equipped with a self-position estimating device and can travel in a guideless manner.

A "position estimating device" is a device that estimates one's own position on a map based on sensor data acquired by an external sensor such as a laser range finder.

The "external world sensor" is a sensor that senses the external state of a moving object. External sensors include, for example, laser range finders (also referred to as range sensors), cameras (or image sensors), LIDAR (Light Detection and Ranging), millimeter wave radars, ultrasonic sensors, and magnetic sensors.

The "internal world sensor" is a sensor that senses the internal state of a moving body. Internal sensors include, for example, rotary encoders (hereinafter sometimes simply referred to as "encoders"), acceleration sensors, and angular acceleration sensors (eg, gyro sensors).

"SLAM" is an abbreviation for Simultaneous Localization and Mapping, which means self-location estimation and map creation at the same time.

In the embodiment described below, it is assumed that the external sensor is a laser range finder (LRF). However, LIDAR may also be used.

<Basic configuration of mobile object in the present disclosure>



See FIG. 1A. In the exemplary embodiment shown in FIG. 1A, the mobile object 10 of the present disclosure includes a laser range finder 102 that scans the environment (around the mobile object 10) and periodically outputs scan data. Below, the laser range finder 102 will be abbreviated as "LRF102". The LRF 102 is a device that measures distance using a laser beam emitted from a laser element. The LRF 102 scans the environment by periodically emitting a laser beam of, for example, infrared or visible light. The laser beam is reflected by surfaces such as structures such as walls and pillars, and objects placed on the floor. The LRF 102 receives the reflected light of the laser beam, calculates the distance to each reflection point, and outputs measurement result data indicating the position of each reflection point. The arrival direction and distance of the reflected light are reflected in the position of each reflection point. Measurement result data (scan data) is sometimes called "environmental measurement data" or "sensor data."

As a distance calculation method, the LRF 102 employs, for example, a TOF (Time Of Flight) method or a phase difference method. In the TOF method, the LRF 102 calculates the time required for the laser beam to travel back and forth from the difference between the time when the laser beam is emitted and the time when the reflected light is received. The product of the speed of light and the round trip time indicates the round trip distance to the reflection point. Thereby, the LRF 102 can acquire data on the distance to the reflection point. In the phase difference method, the LRF 102 modulates the intensity of continuous light at a predetermined frequency and emits it, and detects the phase difference between the modulated emitted light and the received reflected light. A phase difference occurs between the phase of the emitted light and the phase of the reflected light depending on the round trip distance (optical path length) to the reflection point. By detecting the phase difference, the LRF 102 can acquire data on the distance to the reflection point. Note that phase delay can be detected for a maximum of 360 degrees, that is, for one wavelength. By using multiple waves (complex waves) with different modulation frequencies, distance resolution (phase resolution) and measurement distance can be increased.

The environment scan by the LRF 102 is performed, for example, in an angular range of 135 degrees left and right (total 270 degrees) with the front of the LRF 102 as a reference. Specifically, the LRF 102 emits a pulsed laser beam while changing its direction at every predetermined step angle within a horizontal plane, and detects the reflected light of each laser beam. The LRF 102 measures the distance for each step angle using the relationship between the emitted laser beam and the reflected light. If the step angle is 0.3 degrees, measurement data of the distance to the reflection point in the direction determined by the angle for a total of 901 steps can be obtained. In this example, the scan of the surrounding space performed by the LRF 102 is substantially parallel to the floor and is planar (two-dimensional). However, the LRF 102 may also perform three-dimensional scanning.

For the LRF 102, the distance at which measurement is guaranteed is determined at the time of design. In the present disclosure, the LRF 102 can acquire distance data indicating the distance to a reflection point that is within a distance of, for example, 30 m.

Hereinafter, the start time of the scan in the 270 degree range may be referred to as "scan time" for convenience. For example, when scanning is performed by sequentially emitting a laser beam at each step angle from -135 degrees to +135 degrees, the time when the laser beam is emitted in the angular direction of -135 degrees is called the "scan time".

A typical example of scan data may be represented by the position coordinates of each point making up a point cloud acquired for each scan. The position coordinates of the points are defined by a local coordinate system that moves together with the moving body 10. Such a local coordinate system may be called a mobile coordinate system or a sensor coordinate system. In the present disclosure, the origin of the local coordinate system fixed to the moving body 10 is defined as the "position" of the moving body 10, and the orientation of the local coordinate system is defined as the "posture" of the moving body 10. Hereinafter, the position and posture may be collectively referred to as a "pose."

When displayed in a polar coordinate system, the scan data may consist of a set of numerical values indicating the position of each point in terms of "direction" and "distance" from the origin in the local coordinate system. However, if no reflected light is detected, no point exists for that angle. A polar coordinate system representation may be converted to a rectangular coordinate system representation. In the following description, for the sake of simplicity, it is assumed that the scan data output from the LRF 102 is displayed in an orthogonal coordinate system.

The mobile object 10 shown in FIG. 1A is capable of both creating an environmental map (hereinafter referred to as a "map") and moving autonomously while referring to the created map. can. However, it is not essential for the moving body 10 to perform both. In this embodiment, it is only necessary to be able to at least create a map.

The mobile body 10 includes a storage device 104 and a signal processing circuit 106. The storage device 104 stores and updates a map created from the scan data while accumulating scan data when creating a map, and stores a map created in advance during autonomous movement. Note that the number of stored maps may be not one but multiple.

The signal processing circuit 106 is, for example, a semiconductor integrated circuit, and may be a CPU (Central Processing Unit), an MPU (Micro Processing Unit), or an ASIC (Application Specific IC). The signal processing circuit 106 operates as a map creation device when creating a map, and operates as a position estimating device during autonomous movement after map creation.

When creating a map, the signal processing circuit 106 arranges a point group of scan data acquired from the LRF 102 according to the angle and distance at which the laser beam was irradiated. As a result, a partial map regarding the scan range is obtained. Subsequently, the signal processing circuit 106 updates the partial map using the position coordinates of the point group obtained by scanning at the next scan time. The "positional coordinates" referred to here may be expressed as relative coordinates based on the position where the scan data was previously acquired, or as absolute coordinates conveniently set by the user. By repeating the above process, the partial map is updated one after another, and finally a map of the entire scanned area is obtained.

Note that the change in pose can be detected using, for example, odometry information of the moving object 10. For example, if the moving body 10 is an AGV having multiple drive wheels, the distance and direction traveled by the moving body 10 can be estimated by integrating the rotational speed of each drive wheel or the number of rotations per unit time. can. Information about the rotational speed of each drive wheel or the number of rotations per unit time is sometimes called "odometry information." By detecting changes in the pose of the moving object 10 using odometry information, it is possible to estimate at which position on the map the new point group was acquired. Odometry information is prone to errors due to factors such as wheel slipping or wear. Therefore, the mobile object 10 may create a map while detecting pose changes using SLAM technology using the LRF 102. Note that the mobile object 10 can use odometry information not only when creating a map but also when moving while estimating its own position. The mobile object 10 can estimate its own position using both the scan by the LRF 102 and the odometry information.

A plurality of sets of points obtained by respectively performing scans at different scan times may include reflection points indicating approximately similar positions of the same object existing in the environment. If all the points were reflected on the map as separate and independent points, the amount of map data would become extremely large. Therefore, in order to limit the amount of data, the signal processing circuit 106 may divide the map into meshes and limit the number of scan data so that one section of the mesh includes only one reflection point. The size of one section of the mesh may be, for example, 10 cm square in the actual environment.

During autonomous movement after map creation, the signal processing circuit 106 performs matching between the scan data acquired from the LRF 102 and the map read from the storage device 104, and estimates the pose of the mobile object 10. This matching is called pattern matching or scan matching, and can be performed according to various algorithms. A typical example of a matching algorithm is the Iterative Closest Point (ICP) algorithm. Note that the map read from the storage device 104 may be a map created by the mobile object 10 itself, or may be a map created by another device.

In the illustrated example, the moving body 10 further includes a drive device 108, a travel control device 110, a communication circuit 112, and an input device 114. The drive device 108 is a device that generates a driving force for moving the moving body 10. Examples of drive devices 108 include wheels rotated by electric motors or engines, bipedal or multipedal walking devices operated by motors or other actuators. The wheels may be omnidirectional wheels such as mecanum wheels. Furthermore, the moving object 10 may be a moving object that moves in the air or water, or a hovercraft, and the drive device 108 in that case includes a propeller rotated by a motor.

The travel control device 110 operates the drive device 108 to control movement conditions (speed, acceleration, movement direction, etc.) of the mobile body 10. The travel control device 110 may move the moving body 10 along a predetermined travel route, or may move the moving body 10 according to a command given from the outside. The signal processing circuit 106 calculates estimated values of the position and orientation of the moving body 10 while the moving body 10 is moving or stopped. The travel control device 110 controls the travel of the mobile object 10 with reference to this estimated value.

The signal processing circuit 106 and the cruise control device 110 may be collectively referred to as a cruise control device (control system) 120. Travel control device 120 may include a processor and a memory that stores a computer program that controls the operation of the processor. Such a processor and memory may be implemented by one or more semiconductor integrated circuits.

The communication circuit 112 is a circuit through which the mobile body 10 connects to a communication network including an external management device, another mobile body, an operator's mobile terminal device, etc., and exchanges data and/or commands. Communication circuit 112 may perform both wireless and/or wired communication.

The input device 114 is a device that accepts user instructions. The input device 114 can be used to receive a designation of a detection range (distance, angle range) of a point cloud used for map creation when creating a map, which will be described later. The input device 114 can also be used to receive commands regarding travel conditions and travel routes. The input device 114 is, for example, an input terminal that receives commands from the outside, or a physical button provided on the moving body 10. If mobile body 10 is provided with a touch panel display, input device 114 may be a touch panel or software buttons.

A typical example of the storage device 104 described above is realized by a storage device that is mounted on the mobile body 10 and moves together with the mobile body 10. However, the storage device 104 is not limited to this example. Storage device 104 may be a storage device or a database that is located external to mobile 10 and can be connected to mobile 10 by communication circuitry 112. When the storage device 104 is realized by such an external storage device or database, after scan data that can be used for map creation is transmitted from the mobile body 10 to the storage device 104, signals from other than the mobile body 10 are transmitted. The processing circuit may also create the map. In other words, it is not essential for the mobile object 10 to create a map. Furthermore, it is also possible for a plurality of moving objects 10 to read necessary map data from a common storage device 104 as appropriate and perform autonomous driving.

FIG. 1B shows the configuration of an embodiment of a mapping system 300 according to the present disclosure. The map creation system 300 creates a map that the mobile object 10 refers to in order to estimate its own position. The map creation system 300 includes an LRF 102 and a signal processing circuit 106. These configurations and functions are the same as those of the LRF 102 and signal processing circuit 106 provided in the mobile body 10 shown in FIG. 1A. However, the signal processing circuit 106 only needs to have a function of performing map creation processing, and position estimation processing for autonomous driving is not essential.

The map creation system 300 may be provided in one device such as the mobile object 10, or the LRF 102 and the signal processing circuit 106 may have separate and independent casings as two devices. In the latter case, the devices only need to be connected to each other via communication lines so that they can send and receive data. For example, the signal processing circuit 106 may be realized by one PC, and the LRF 102 may be installed on a cart that is moved manually. It is only necessary that the PC and the LRF 102 be connected by wire or wirelessly. A storage device 104 for storing map data created by the signal processing circuit 106 may be provided as appropriate. For example, the signal processing circuit 106 and the storage device 104 may be the CPU 51 and the memory 52 of the traffic management device 50, which will be described later with reference to FIGS. 14 and 20, respectively. As another example, the map creation system 300 temporarily stores the scan data acquired by the LRF 102 in a storage device such as a flash memory, connects the storage device to the signal processing circuit 106, and the signal processing circuit 106 creates the map. It can also include form.

Next, while illustrating the mobile object 10 of FIG. 1A, it will be explained that there is a large scope for improving accuracy in the conventional map creation method.

FIG. 2 schematically shows a plurality of laser beams (solid lines) emitted from the LRF 102 of the moving body 10 for each step angle. For convenience of explanation, the step angle is shown very large. The following explanation will focus on the laser beam 15a, but the same explanation applies to other laser beams.

The emitted laser beam does not become perfectly parallel light even after passing through the collimating lens, and has a divergence angle that is not 0 degrees. Therefore, the cross section of the laser beam on a plane perpendicular to the optical axis becomes larger as it goes farther away. In FIG. 2, the laser beam 15a is shown as a straight line, but in reality, a beam 15w having a spread is emitted. Note that the shape of the beam 15w is also only shown schematically. In the present disclosure, since the scanning of the surrounding space performed by the LRF 102 is substantially parallel to the floor surface, the spread of the laser beam in the direction perpendicular to the floor surface is not considered.

A laser beam with such a spread can cause a detection error in the direction in which an object exists.

FIG. 3 is a diagram for explaining the detection error of the laser beam 15w having a spread. Assume that a laser beam is emitted from the LRF 102 in the direction of an angle θa. The angle is an angle calculated from an arbitrary reference line S. Assuming that the diameter is constant and sufficiently thin, a laser beam 15a will be emitted. The laser beam 15a is reflected only by the object Ga existing on the optical axis and returns to the LRF 102. The laser beam 15a is not reflected by the object Gb or Gc that exists in the direction of the angle θb or the angle θc that is deviated from the optical axis.

However, as described above, the laser beam 15w having a spread is emitted from the LRF 102. The laser beam 15w is reflected not only by the object Ga existing in the direction of the angle θa, but also by the object Gb existing in the direction of the angle θb and the object Gc existing in the direction of the angle θc. That is, all objects existing between angles θb and θc are detected as objects existing in the direction of angle θa. As a result, a detection error occurs.

FIG. 4 is a diagram for explaining that the laser beam 15w having a spread increases the detection error. The laser beam 15w has a width H _L1 at a position away from the LRF 102 by a distance L1, but has a width H L2 (>H L1 ) at a position away from the LRF 102 by a distance _L2 (> _L1 ). All objects existing within the width H _L2 are detected as objects existing in that angular direction. It is understood that a larger detection error occurs when the laser beam 15w is reflected at a distance L2 than when it is reflected at a distance L1. Specifically, when L2 = 30 m, H _L2 = 30 to 40 cm. When scanning is performed using the laser beam 15w that causes such a detection error, an actually existing object is detected as a larger object.

FIG. 5 is a diagram for explaining that an actually existing object G _real is detected as a larger object G _virtual . Assume that scanning is performed along the direction from -X to +X in the figure. First, the first reflection of G _real is detected at the +X side beam end of the wide laser beam 15w-1. As a result, the object G _real is detected to have an end at a position that is wider on the -X side than it actually is by the radius of the beam. The scan continues, and the last reflection of the object G _real is detected at the -X side beam end of the wide laser beam 15w-2. As a result, the object G _real is detected to have an end at a position that is wider than the actual position on the +X side by the radius of the beam. That is, the actual object G _real is detected as a larger object G _virtual . As described with reference to FIG. 4, the farther away the reflection occurs, the larger the detection error becomes, and the object G _virtual is detected to be larger than the actual object G _real .

FIG. 6A is a plan layout diagram schematically showing an example of an environment 200 in which the mobile object 10 moves. Environment 200 is part of a broader environment. In FIG. 6A, a thick straight line indicates, for example, a fixed wall 202 of a building. Assume that the mobile object 10 performs a scan at the position shown in FIG. 6A and creates a map.

FIG. 6B shows a map 202M created by arranging the acquired point clouds. For reference, the fixed wall 202 of the building is shown as a solid line. The detection error of the position of each point included in the point groups 202M-1, 202M-2, and 202M-3 increases as the position is farther from the moving body 10, and the distortion of the map increases. The existence of such distortion affects the running accuracy of other moving objects 10 that autonomously move while referring to the map.

The inventors of the present application have conducted studies to improve the accuracy of maps to be created and to make it possible to more accurately estimate one's own position during autonomous driving. As a result, the inventor of the present invention considered that the detection error of the laser beam 15w can actually affect the accuracy of the map when the intensity of reflected light received from a distance is large. For example, when specular reflection or retroreflection of the laser beam 15w occurs on the surface of a distant object, the intensity of the reflected light increases. If specular reflection or retroreflection does not occur, even if the outer edge of the expanded laser beam 15w is reflected on the surface of a distant object, the intensity of the reflected light will be small and it will be treated as noise, resulting in a detection error in the position of the reflection point. It does not actually occur. However, when specular reflection or retroreflection occurs on the surface of a distant object, the intensity of the reflected light from the outer edge of the expanded laser beam 15w is also large, so it is not treated as noise, and the detection error of the position of the reflection point is ignored. become unable. As a result, if a map is created using the position of the reflection point, distortion will become large.

Through the above studies, the inventor of the present application obtained the following map creation system.

A map creation system 300 (FIG. 1B) according to the present disclosure includes an LRF 102 and a signal processing circuit 106. The LRF 102 emits a laser beam while changing the angle within a first angle range (for example, within a range of 270 degrees) and acquires reflected light. Then, the LRF 102 uses the relationship between the emitted laser beam and the reflected light to acquire distance data indicating the distance to a reflection point that is within a first measurable distance (for example, within 30 m) for each angle. . Examples of the "relationship" here include, for example, the time difference between the emission time of the laser beam and the detection time of the reflected light, or the phase difference between the phase of the emitted laser beam and the phase of the reflected light.

The signal processing circuit 106 selects one or more partial areas smaller than the measurable area from the measurable area defined by the first angular range and the first distance, and selects one or more partial areas smaller than the measurable area, and calculates the reflection included in the one or more partial areas. Create a map using distance data that shows distances to points. Examples of one or more partial areas smaller than the measurable area are typically the following two.

In a first example, a partial area defined by a first angular range (for example a range of 270 degrees) and at least one second distance shorter than the first distance (for example 10 m) is selected. This means that a map is created using reflection points of objects that exist in a relatively close range. The second distance may be fixed or variable.

In a second example, the partial area is defined by at least one second angular range (e.g. 120 degrees) smaller than the first angular range (e.g. 270 degrees) and the first distance (e.g. 30 m). selected. The second example assumes that a map is created using reflected light from the remaining angular ranges after excluding some angular ranges. In the second example, a threshold for the intensity of reflected light (intensity threshold) is set depending on the distance at which the reflection point exists. If strong reflected light is obtained near the first distance (30 m), the detection error of what can be adopted as scan data becomes large. Therefore, the signal processing circuit 106 compares the intensity of the reflected light with an intensity threshold corresponding to the distance to the reflection point of the object, and if the intensity of the reflected light is greater than the intensity threshold, the signal processing circuit 106 determines the direction from which the reflected light has arrived. Exclude angle range to include. The signal processing circuit 106 then creates a map using the remaining reflection points existing in the at least one second angle range. The second angular range may be variable. This is because the direction in which the strong reflected light is received may change as the moving body 10 travels.

As the moving body 10 moves, the relative distance between the moving body 10 and the object changes. For the excluded angular range, the signal processing circuit 106 continues to compare the intensity of the reflected light with an intensity threshold value corresponding to the distance to the reflection point of the object, which changes every moment. When the intensity of the reflected light falls below the intensity threshold, the signal processing circuit 106 incorporates the range below the intensity threshold into the second angular range, and creates a map using the reflection points existing in the second angular range. do.

Hereinafter, the above-mentioned first and second examples will be specifically explained with reference to FIGS. 7 to 10.

FIG. 7 shows the moving body 10 and the measurable area SA of the moving body 10. The measurable area SA is defined by the angle range θ and the maximum measurement distance L _MAX . The basic moving object 10 creates a map using reflection points detected within the measurable area SA while moving in the direction of the white arrow, or creates a map using reflection points detected within the measurable area SA and the map. The robot then moves autonomously.

First, the above-mentioned first example will be explained. The first example is an example in which the detection area of reflection points used for map creation is fixed to a smaller area.

FIG. 8A shows the relationship between the measurable area SA and the partial area SB used by the mobile object 10 when creating a map. As shown in FIG. 8A, the partial area SB is smaller than the measurable area SA. More specifically, the partial area SB is defined by the same angle range θ as the measurable area SA and a distance threshold L _TH that is smaller than the maximum measurement distance L _MAX of the measurable area SA. The mobile object 10 creates a map using the reflection points posted within the partial area SB. The object G shown in FIG. 8A will be explained as an example. The object G is, for example, a shelf installed in the environment. Note that the following explanation will focus on distance, assuming that the object G exists within the angular range θ.

FIG. 8B shows the positional relationship between the moving body 10 and the object G when the moving body 10 moves and approaches the object G. The LRF 102 also measures reflection points in an area that is included in the measurable area SA but not included in the partial area SB (an area outside the partial area SB). Therefore, the output of the LRF 102 includes the distance to the reflection point on the object G. However, the signal processing circuit 106 does not create a map using reflection points on the object G located at a position farther than the distance threshold _LTH .

FIG. 8C shows the positional relationship between the moving body 10 and the object G when the moving body 10 moves further and approaches the object G. When the signal processing circuit 106 detects that the distance to the reflection point on the object G is less than or equal to the distance threshold LTH, it creates a map using the distance data to the reflection point. FIG. 8C shows a point group 204 indicating the positions of reflection points on the surface of the object G on the moving body 10 side.

The above processing means that the signal processing circuit 106 selects the partial area SB from the measurable area SA and creates a map using reflection points from areas included in the partial area SB. Thereby, the detection error (distortion) that may be included in the position of the reflection point farther than the distance threshold _LTH can be suppressed to a smaller level.

The distance threshold _LTH can be set in any way. For example, even if a predetermined distance threshold L _TH is stored in the storage device 104 as selection reference data, and the signal processing circuit 106 reads out the selection reference data from the storage device 104 and sets it as the distance threshold L _TH . good. Alternatively, the user may input a value via the input device 114, and the signal processing circuit 106 may set the value as the distance threshold _LTH . In other words, the input device 114 can receive the specification of a partial area from the user.

In an exemplary embodiment, the distance threshold L _TH may be a distance less than 25 m, such as 20 m, 15 m or 10 m, where the maximum measured distance L _MAX is 30 m.

Next, the above-mentioned second example will be explained. The second example is an example in which the detection area of reflection points used for map creation is variably set to a smaller area.

FIG. 9A shows the measurable area SA of the mobile object 10 at the time of map creation. The measurable area SA at this time is the same as the example shown in FIG. As the moving body 10 travels, the relative distance between the moving body 10 and the object G becomes smaller. As a result, the relative distance becomes within the maximum measurement distance L _MAX , and the object G enters the measurable area SA.

FIG. 9B shows the positional relationship between the moving body 10 and the object G when the object G enters the measurable area SA. As described with reference to FIG. 5, FIG. 9B schematically shows that the actual object G shown by diagonal lines is detected as a larger object, as shown by the broken line.

In this example, the signal processing circuit 106 acquires the intensity of the reflected light from the object G from the LRF 102 for each step angle, together with distance data. The signal processing circuit 106 uses the distance data to detect that the object G exists within the measurable area SA. Further, the signal processing circuit 106 compares the intensity data with a predetermined intensity threshold _ITH for each detected distance, and determines whether the intensity of the reflected light from the object G exceeds the predetermined intensity threshold _ITH . Determine. The intensity threshold value I _TH is a threshold value related to the intensity of reflected light, which is prepared in advance. The storage device 104 stores selection criteria data that associates distances with intensity thresholds _ITH . The selection criteria data may be stored as a function of the distance and the intensity threshold _ITH , or may be stored as a table that associates each of a plurality of distance values with the intensity threshold _ITH . The signal processing circuit 106 reads out the selection reference data from the storage device 104 and holds an intensity threshold value _ITH corresponding to the distance. For example, the intensity threshold I _TH for the maximum measurement distance L _MAX (eg, 30 m) is set to a value smaller than the reflection intensity detected when specular reflection or retroreflection occurs.

The signal processing circuit 106 determines that the object G exists within the measurable area SA and that the intensity of the reflected light from the object G exceeds an intensity threshold _ITH determined according to the distance to the object G. When detected, the signal processing circuit 106 sets a part of the measurable area SA that includes the reflection point of the object G as an exclusion area SV. Then, the signal processing circuit 106 selects an area other than the excluded area SV in the measurable area SA as an area for creating a map. For example, if a function is adopted in which the intensity threshold value I _TH is larger as the distance is smaller and smaller as the distance is larger, a region including a reflection point with a large intensity despite the large distance can be set as the exclusion region SV.

FIG. 9C illustrates the excluded region SV within the measurable region SA and the selected partial regions SB-1 and SB-2. The signal processing circuit 106 sets an area defined by at least the angular range θ _SV in which the object G was detected and the maximum measurement distance L _MAX as an exclusion area SV. The signal processing circuit 106 does not use the reflection points in the exclusion region SV to create the map, but uses the reflection points in the partial regions SB-1 and SB-2 to create the map. The partial area SB-1 is defined by an angular range θ _B-1 smaller than the angular range θ and a maximum measurement distance L _MAX . The partial area SB-2 is defined by an angular range θ _B-2 smaller than the angular range θ and a maximum measurement distance L _MAX . Note that in the present disclosure, two partial areas SB-1 and SB-2 are illustrated as remaining areas, but the number of partial areas may be one, or three or more. It is sufficient that at least one partial area is selected.

Note that the reflected light acquired from the partial areas SB-1 and SB-2 may also include reflected light from the position of the maximum measurement distance L _MAX . However, as described above, even if the outer edge portion of the spread laser beam 15w is reflected by the object surface, the intensity of the reflected light is so small that it can be treated as noise and is not used for map creation. Therefore, partial areas SB-1 and SB-2 may extend up to the maximum measurement distance L _MAX .

FIG. 9D shows the positional relationship between the moving body 10 and the object G when the moving body 10 continues to move. Even after setting the exclusion region SV, the signal processing circuit 106 continuously acquires distance data and intensity data of the object G from the LRF 102. The signal processing circuit 106 uses the distance data and the selection reference data to obtain an intensity threshold I _TH corresponding to the current distance of the object G, and compares the intensity data with the intensity threshold I _TH . FIG. 9D shows an example where the intensity data is still slightly larger than the intensity threshold _ITH . For reference, the position where the intensity data and the intensity threshold value _ITH generally match is shown by a broken line arc touching the object G.

FIG. 9E shows the positional relationship between the moving body 10 and the object G when the intensity of the reflected light from the object G becomes equal to or less than the intensity threshold value _ITH . The distance between the moving body 10 and the object G at this time is shown as a distance _LSV . Note that the intensity threshold value _ITH at this time is also determined according to the distance to the reflection point that gave the intensity data. When the signal processing circuit 106 detects that the intensity data has become equal to or less than the intensity threshold I _TH , the signal processing circuit 106 creates a partial area SB-3 defined by the angular range θ _SV and the distance L _SV shorter than the maximum measurement distance L _MAX . , is additionally selected as the detection area of the reflection point used for map creation. The angular range θ _SV of the partial region SB-3 is a range other than the angular ranges θ _B-1 and θ _B-2 of the entire angular range θ. FIG. 9E shows a point group 204 indicating the positions of reflection points on the surface of the object G on the moving body 10 side.

The reason for selecting the additional partial area SB-3 is to reflect the object G on the map when the detection error of the object G falls within an acceptable range. For example, when the moving body 10 approaches an object with a high intensity of reflected light and passes nearby, the exclusion region SV changes dynamically. Without the above-mentioned angle range addition process, the area where the object exists will always be set as the exclusion area SV, and the object will not be reflected on the map. The fact that the intensity of the reflected light has become equal to or less than the intensity threshold value I _TH can be considered to mean that the relative distance between the moving body 10 and the object G has become small, and the detection error of the object G has fallen within an allowable range. If the object G is reflected on the map at that point, the accuracy of the map can be guaranteed.

In the example of FIG. 9C, an exclusion region SV is first set, and remaining partial regions SB-1 and SB-2 are determined. However, it is not necessary to set the exclusion area SV at that point. When the signal processing circuit 106 detects that the object G has simply entered the measurable area SA, the area where the intensity of all reflected light including the object G is equal to or less than the intensity threshold according to the distance is designated as a partial area SB-. 1 and SB-2.

FIG. 10 shows a map 204M created by arranging the point clouds acquired by the operations of the first example or the second example described above in the environment 200 in which the mobile object 10 moves. Similar to FIG. 6B, the fixed wall 202 of the building is shown by a solid line for reference. Unlike the example in FIG. 6B, due to the operation of the first or second example described above, reflection points located further away than the distance threshold L _TH are not used for map creation, and reflection points located closer than the distance threshold L _TH are used. Reflection points are used to create maps. As a result, the detection error of the position of each point included in the point groups 204M-1 and 204M-2 becomes sufficiently small. It is assumed that the point group 204M-3 is obtained by performing the operation of the first example or the second example described above before the moving body 10 reaches the position shown in FIG. 6A.

Next, a processing flow when the mobile body 10 performs the above processing will be described as an example with reference to FIGS. 11 to 13. Each processing flow is executed by the signal processing circuit 106.

FIG. 11 is a diagram showing a process flow for creating a map with a limited measurement range.

In step S10, the signal processing circuit 106 sends a command to the LRF 102 to start emitting a laser beam. In this example, the surrounding environment is scanned by emitting a laser beam at every step angle of 0.3 degrees from -135 degrees to +135 degrees.

In step S12, the signal processing circuit 106 acquires distance data for each step angle from the LRF 102. The distance data is calculated by the LRF 102 using the relationship between the emitted laser beam and the received reflected light. Since the "relationship" is as described above, further explanation will be omitted. Note that the signal processing circuit 106 may receive position coordinate data and distance data of a set of reflection points from the LRF 102 for each step angle, or may receive azimuth data and distance data of the reflection points from the LRF 102. Note that the orientation is known because it changes for each step angle. It is not essential to include orientation data as long as the obtained distance data is ordered and arranged.

In step S14, the signal processing circuit 106 selects one or more partial regions from the measurable region. A partial area is a subset of a measurable area.

In step S16, the signal processing circuit 106 creates a map using the distance data included in the selected partial area, and ends the process.

12A and 12B are variations of the specific process of step S14 in FIG. 11.

FIG. 12A shows a first processing flow for selecting a partial area. The first processing flow corresponds to the processing of the first example described above.

In step S22, the signal processing circuit 106 reads selection reference data from the storage device 104. The selection criterion data is a numerical value indicating the distance threshold _LTH .

In step S24, the signal processing circuit 106 acquires all distance data within the measurable area SA from the LRF 102.

In step S26, the signal processing circuit 106 selects the area defined by the angle range θ and the distance threshold _LTH as the partial area SB.

Through the processes in step S26 and step S16 (FIG. 11) described above, distance data that is less than or equal to the distance threshold LTH is selected from all the distance data and used for creating the map. Note that in the process of FIG. 12A, it is assumed that the angle range θ is the same as the scan range of the LRF 102 and is known.

FIG. 12B shows a second processing flow for selecting a partial area. The second processing flow corresponds to the processing of the second example described above.

In step S32, the signal processing circuit 106 acquires selection criteria data from the storage device 104. The selection criterion data is a numerical value indicating an intensity threshold value _ITH depending on the distance.

In step S34, the signal processing circuit 106 acquires distance data and reflected light intensity data from the LRF 102 for each scan angle.

In step S36, the signal processing circuit 106 determines a scan angle such that intensity data at a certain distance≧intensity threshold value _ITH at that distance.

In step S38, the signal processing circuit 106 determines the area including the determined scan angle as the exclusion area SV, and selects an area other than the exclusion area SV in the measurable area SA as a partial area. In the example of FIG. 9, signal processing circuit 106 selects one or more partial areas SB-1 and SB-2. Reflection points within the selected subregion are used to create the map. Thereafter, as the mobile object 10 continues to move, the signal processing circuit 106 executes steps S40 and 42 below.

In step S40, the signal processing circuit 106 determines, among the reflection points within the exclusion region SV, a reflection point for which intensity data at a certain distance≦intensity threshold value _ITH at that distance.

In step S42, the signal processing circuit 106 additionally selects a region including the determined reflection point as a partial region. In the example of FIG. 9, signal processing circuit 106 selects partial area SB-3 in addition to partial areas SB-1 and SB-2. The reflection points within the selected partial area SB-3 are further used to create a map.

FIG. 13 is a list diagram for explaining the difference in measurement areas used by the mobile body 10 at the time of map creation and self-position estimation. The biggest difference is that the partial area SB used in the example using the distance threshold _LTH (first example above, FIG. 12A) is smaller than the measurement area SA of the LRF 102 used by the moving body to estimate its own position. It is also narrow. Alternatively, the sum of the partial areas SB-n (n: an integer of 1 or more) used in the example of using the intensity threshold _ITH (the above-mentioned second example, FIG. 12B) is This is narrower than the maximum measurement area SA of the LRF 102 used for this purpose. Since the detection error of the position of the reflection point within the selected partial area is within the permissible range, by creating a map using the reflection point, it is possible to improve the accuracy of the map to be created.

<Exemplary Embodiment>



Hereinafter, embodiments of a mobile object according to the present disclosure will be described in more detail. In this embodiment, an automatic guided vehicle is cited as an example of a moving object. In the following description, the automatic guided vehicle will be described as "AGV" using an abbreviation. Hereinafter, the reference numeral "10" will be given to "AGV" as well, similar to the mobile object 10. Note that the component corresponding to the storage device 104 is a "memory" described later, and the component corresponding to the signal processing circuit 106 is a "microcomputer 14a", a "position estimation device 14e", or a "chip circuit 14g" including these, described later. ”.

(1) Basic configuration of the system



FIG. 14 shows an example basic configuration of an exemplary mobile management system 100 according to the present disclosure. Mobile body management system 100 includes at least one AGV 10 and an operation management device 50 that manages operation of AGV 10. FIG. 14 also shows a terminal device 20 operated by the user 1.

The AGV10 is an unmanned guided vehicle that can run in a "guideless" manner, requiring no guides such as magnetic tape. The AGV 10 can estimate its own position and transmit the estimation results to the terminal device 20 and the traffic management device 50. The AGV 10 is capable of automatically traveling within the environment S according to commands from the operation management device 50.

The traffic management device 50 is a computer system that tracks the position of each AGV 10 and manages the travel of each AGV 10. The traffic management device 50 may be a desktop PC, a notebook PC, and/or a server computer. Traffic management device 50 communicates with each AGV 10 via a plurality of access points 2. For example, the traffic management device 50 transmits to each AGV 10 data on the coordinates of the position to which each AGV 10 should go next. Each AGV 10 periodically transmits data indicating its own position and orientation to the traffic management device 50, for example, every 250 milliseconds. When the AGV 10 reaches the designated position, the traffic management device 50 further transmits data on the coordinates of the next position. The AGV 10 can also travel within the environment S according to the user's 1 operation input to the terminal device 20. An example of the terminal device 20 is a tablet computer.

FIG. 15 shows an example of an environment S in which three AGVs 10a, 10b, and 10c exist. It is assumed that both AGVs are traveling in the depth direction in the figure. The AGVs 10a and 10b are transporting cargo placed on the top plate. The AGV 10c is running following the AGV 10b in front. Note that, for convenience of explanation, reference numerals 10a, 10b, and 10c are given in FIG. 15, but hereinafter, they will be described as "AGV10".

In addition to the method of transporting the cargo placed on the top plate, the AGV 10 can also transport the cargo by using a tow truck connected to itself. FIG. 16 shows the AGV 10 and the tow truck 5 before being connected. Each leg of the tow truck 5 is provided with a caster. The AGV 10 is mechanically connected to the tow truck 5. FIG. 17 shows the connected AGV 10 and tow truck 5. When the AGV 10 runs, the tow truck 5 is towed by the AGV 10. By towing the towing truck 5, the AGV 10 can transport the cargo placed on the towing truck 5.

The connection method between the AGV 10 and the towing truck 5 is arbitrary. An example will be explained here. A plate 6 is fixed to the top plate of the AGV10. The tow truck 5 is provided with a guide 7 having a slit. The AGV 10 approaches the tow truck 5 and inserts the plate 6 into the slit of the guide 7. When the insertion is completed, the AGV 10 allows an electromagnetic locking pin (not shown) to pass through the plate 6 and the guide 7 to apply an electromagnetic lock. Thereby, the AGV 10 and the tow truck 5 are physically connected.

Refer to FIG. 14 again. Each AGV 10 and the terminal device 20 are connected, for example, on a one-to-one basis, and can perform communication based on the Bluetooth (registered trademark) standard. Each AGV 10 and the terminal device 20 can also perform communication based on Wi-Fi (registered trademark) using one or more access points 2. The plurality of access points 2 are connected to each other via a switching hub 3, for example. Two access points 2a and 2b are shown in FIG. 14. The AGV 10 is wirelessly connected to the access point 2a. The terminal device 20 is wirelessly connected to the access point 2b. The data transmitted by the AGV 10 is received by the access point 2a, transferred to the access point 2b via the switching hub 3, and transmitted from the access point 2b to the terminal device 20. Furthermore, data transmitted by the terminal device 20 is received by the access point 2b, then transferred to the access point 2a via the switching hub 3, and transmitted from the access point 2a to the AGV 10. Thereby, bidirectional communication between the AGV 10 and the terminal device 20 is realized. The plurality of access points 2 are also connected to a traffic management device 50 via a switching hub 3. Thereby, bidirectional communication is also realized between the traffic management device 50 and each AGV 10.

(2) Creating a map



In order to enable the AGV 10 to travel while estimating its own position, a map within the environment S is created. The AGV 10 is equipped with a position estimation device and an LRF 102, and can create a map using the output of the LRF 102.

The AGV 10 transitions to data acquisition mode by a user's operation. In the data acquisition mode, the AGV 10 starts acquiring sensor data using the LRF 102.

The position estimation device stores sensor data in a storage device. When the acquisition of sensor data in the environment S is completed, the sensor data accumulated in the storage device is transmitted to the external device. The external device is, for example, a computer having a signal processing processor and installed with a cartographic computer program.

The signal processing processor of the external device superimposes the sensor data obtained for each scan. A map of the environment S can be created by repeatedly performing the overlapping process by the signal processor. The map is processed using the above-described map processing device 300 (see FIG. 10). The device 300 creates data indicating the location of a specific area selected from the map. The external device transmits the processed map data to the AGV 10. The AGV 10 stores processed map data in an internal storage device. The external device may be the traffic management device 50 or another device.

The AGV 10 may create and process the map instead of the external device. The processing performed by the signal processing processor of the external device described above may be performed by a circuit such as a microcontroller unit (microcomputer) of the AGV 10. When creating a map within the AGV 10, there is no need to transmit accumulated sensor data to an external device. The data capacity of sensor data is generally considered to be large. Since there is no need to transmit sensor data to an external device, it is possible to avoid occupying a communication line.

Movement within the environment S for acquiring sensor data can be realized by the AGV 10 traveling in accordance with a user's operation. For example, the AGV 10 wirelessly receives, via the terminal device 20, a travel command from a user to instruct movement in each of the forward, backward, left, and right directions. The AGV 10 travels forward, backward, left and right in the environment S according to the travel command, and creates a map. When the AGV 10 is connected by wire to a control device such as a joystick, the AGV 10 may travel forward, backward, left and right in the environment S according to control signals from the control device, and create a map. Sensor data may be acquired by a person pushing a measuring trolley on which the LRF 102 is mounted.

Although a plurality of AGVs 10 are shown in FIGS. 14 and 15, there may be only one AGV. When a plurality of AGVs 10 exist, the user 1 can use the terminal device 20 to select one AGV 10 from among the plurality of registered AGVs to create a map of the environment S.

Once the map is created, each AGV 10 can thereafter travel automatically while estimating its own position using the map.

(3) AGV configuration



FIG. 18 is an external view of an exemplary AGV 10 according to this embodiment. The AGV 10 includes two drive wheels 11a and 11b, four casters 11c, 11d, 11e, and 11f, a frame 12, a conveyance table 13, a travel control device 14, and an LRF 102. Two drive wheels 11a and 11b are provided on the right and left sides of the AGV 10, respectively. Four casters 11c, 11d, 11e and 11f are arranged at the four corners of the AGV 10. Note that the AGV 10 also has a plurality of motors connected to the two drive wheels 11a and 11b, but the plurality of motors are not shown in FIG. 18. Moreover, although FIG. 18 shows one drive wheel 11a and two casters 11c and 11e located on the right side of the AGV 10, and a caster 11f located on the left rear, the left drive wheel 11b and the left front The casters 11d are hidden behind the frame 12 and are not clearly shown. The four casters 11c, 11d, 11e and 11f can rotate freely. In the following description, the drive wheels 11a and 11b are also referred to as wheels 11a and wheels 11b, respectively.

The travel control device 14 is a device that controls the operation of the AGV 10, and mainly includes an integrated circuit including a microcomputer (described later), electronic components, and a board on which they are mounted. The travel control device 14 transmits and receives data to and from the terminal device 20 and performs preprocessing calculations, as described above.

The LRF 102 is an optical device that measures the distance to the reflection point by emitting, for example, an infrared laser beam 15a and detecting the reflected light of the laser beam 15a. In this embodiment, the LRF 102 of the AGV 10 emits a pulsed laser beam 15a, for example, into a space within a range of 135 degrees left and right (270 degrees in total) with the front of the AGV 10 as a reference, while changing the direction every 0.25 degrees. Then, the reflected light of each laser beam 15a is detected. As a result, data on the distance to the reflection point in the direction determined by the angle for a total of 1081 steps can be obtained every 0.25 degrees. Note that in this embodiment, the scanning of the surrounding space performed by the LRF 102 is substantially parallel to the floor surface and is planar (two-dimensional). However, the LRF 102 may also scan in the height direction.

The AGV 10 can create a map of the environment S based on the position and orientation (orientation) of the AGV 10 and the scan results of the LRF 102. The map may reflect the arrangement of structures such as walls and pillars around the AGV, and objects placed on the floor. Map data is stored in a storage device provided within the AGV 10.

The position and orientation of the AGV 10, ie, the pose (x, y, θ), may be hereinafter simply referred to as "position."

As described above, the travel control device 14 compares the measurement results of the LRF 102 with the map data held by the travel control device 14 to estimate its current position. The map data may be map data created by another AGV 10.

FIG. 19A shows a first hardware configuration example of the AGV 10. FIG. 19A also shows a specific configuration of the travel control device 14.

The AGV 10 includes a travel control device 14, an LRF 102, two motors 16a and 16b, a drive device 17, and wheels 11a and 11b.

The travel control device 14 includes a microcomputer 14a, a memory 14b, a storage device 14c, a communication circuit 14d, and a position estimation device 14e. The microcomputer 14a, memory 14b, storage device 14c, communication circuit 14d, and position estimation device 14e are connected by a communication bus 14f, and can exchange data with each other. The LRF 102 is also connected to the communication bus 14f via a communication interface (not shown), and transmits measurement data, which is the measurement result, to the microcomputer 14a, the position estimation device 14e, and/or the memory 14b.

The microcomputer 14a is a processor or a control circuit (computer) that performs calculations to control the entire AGV 10 including the travel control device 14. Typically, the microcomputer 14a is a semiconductor integrated circuit. The microcomputer 14a transmits a PWM (Pulse Width Modulation) signal, which is a control signal, to the drive device 17 to control the drive device 17 and adjust the voltage applied to the motor. This causes each of motors 16a and 16b to rotate at a desired rotational speed.

One or more control circuits (for example, a microcomputer) that control the drive of the left and right motors 16a and 16b may be provided independently of the microcomputer 14a. For example, the motor drive device 17 may include two microcomputers that respectively control the drive of the motors 16a and 16b.

The memory 14b is a volatile storage device that stores computer programs executed by the microcomputer 14a. The memory 14b can also be used as a work memory when the microcomputer 14a and the position estimation device 14e perform calculations.

The storage device 14c is a nonvolatile semiconductor memory device. However, the storage device 14c may be a magnetic recording medium such as a hard disk, or an optical recording medium such as an optical disk. Furthermore, the storage device 14c may include a head device for writing and/or reading data on any recording medium and a control device for the head device.

The storage device 14c stores a map M of the driving environment S, and data R of one or more driving routes (driving route data). The map M is created by the AGV 10 operating in map creation mode and is stored in the storage device 14c. The driving route data R is transmitted from outside after the map M is created. In this embodiment, the map M and the driving route data R are stored in the same storage device 14c, but they may be stored in different storage devices.

An example of travel route data R will be explained.

When the terminal device 20 is a tablet computer, the AGV 10 receives travel route data R indicating the travel route from the tablet computer. The travel route data R at this time includes marker data indicating the positions of a plurality of markers. The "marker" indicates a passing position (way point) of the traveling AGV 10. The travel route data R includes at least position information of a start marker indicating a travel start position and an end marker indicating a travel end position. The travel route data R may further include position information of markers at one or more intermediate waypoints. When the travel route includes one or more intermediate waypoints, the route from the start marker to the end marker via the travel waypoints in order is defined as the travel route. In addition to the coordinate data of the marker, the data for each marker may include data on the direction (angle) and travel speed of the AGV 10 until it moves to the next marker. When the AGV 10 temporarily stops at the position of each marker and performs self-position estimation and notification to the terminal device 20, the data of each marker is the acceleration time required for acceleration to reach the relevant traveling speed, and/or , may include data on the deceleration time required for deceleration from the traveling speed to stopping at the next marker position.

The movement of the AGV 10 may be controlled by the operation management device 50 (for example, a PC and/or a server computer) instead of the terminal device 20. In that case, the traffic management device 50 may instruct the AGV 10 to move to the next marker each time the AGV 10 reaches a marker. For example, the AGV 10 receives from the operation management device 50 the coordinate data of the next destination position, or the distance and angle to the destination position, as driving route data R indicating the driving route.

The AGV 10 can travel along the stored travel route while estimating its own position using the created map and sensor data output by the LRF 102 acquired during travel.

The communication circuit 14d is, for example, a wireless communication circuit that performs wireless communication based on Bluetooth (registered trademark) and/or Wi-Fi (registered trademark) standards. Both standards include wireless communication standards using frequencies in the 2.4 GHz band. For example, in a mode in which a map is created by driving the AGV 10, the communication circuit 14d performs wireless communication based on the Bluetooth (registered trademark) standard, and communicates with the terminal device 20 on a one-to-one basis.

The position estimating device 14e performs map creation processing and self-position estimation processing when the vehicle is traveling. The position estimation device 14e can create a map of the environment S based on the position and orientation of the AGV 10 and the scan results of the LRF 102. During traveling, the position estimation device 14e receives sensor data from the LRF 102, and also reads out the map M and the position data of the specific area stored in the storage device 14c. The self-position (x, y, θ) on the map M is identified by matching the local map data (sensor data) created from the scan results of the LRF 102 with the map M over a wider range. The position estimating device 14e generates "reliability" data indicating the extent to which the local map data matches the map M. The self-location (x, y, θ) and reliability data may be transmitted from the AGV 10 to the terminal device 20 or the traffic management device 50. The terminal device 20 or the traffic management device 50 can receive data on its own position (x, y, θ) and reliability and display it on a built-in or connected display device.

In this embodiment, the microcomputer 14a and the position estimation device 14e are separate components, but this is just an example. It may be one chip circuit or a semiconductor integrated circuit that can independently perform each operation of the microcomputer 14a and the position estimating device 14e. FIG. 19A shows a chip circuit 14g that includes a microcomputer 14a and a position estimation device 14e. An example in which the microcomputer 14a and the position estimation device 14e are provided separately and independently will be described below.

Two motors 16a and 16b are attached to two wheels 11a and 11b, respectively, and rotate each wheel. In other words, the two wheels 11a and 11b are each drive wheels. In this specification, motor 16a and motor 16b will be described as motors that drive the right wheel and left wheel of AGV 10, respectively.

The drive device 17 has motor drive circuits 17a and 17b for adjusting voltages applied to each of the two motors 16a and 16b. Each of motor drive circuits 17a and 17b includes a so-called inverter circuit. The motor drive circuits 17a and 17b turn on or off the current flowing to each motor in response to a PWM signal transmitted from the microcomputer 14a or the microcomputer in the motor drive circuit 17a, thereby adjusting the voltage applied to the motors.

FIG. 19B shows a second example of the hardware configuration of the AGV 10. The second hardware configuration example differs from the first hardware configuration example (FIG. 19A) in that it includes a laser positioning system 14h and that the microcomputer 14a is connected one-to-one with each component. do.

The laser positioning system 14h includes a position estimation device 14e and an LRF 102. The position estimation device 14e and the LRF 102 are connected, for example, by an Ethernet (registered trademark) cable. Each operation of the position estimation device 14e and the LRF 102 is as described above. The laser positioning system 14h outputs information indicating the pose (x, y, θ) of the AGV 10 to the microcomputer 14a.

The microcomputer 14a has various general-purpose I/O interfaces or general-purpose input/output ports (not shown). The microcomputer 14a is directly connected to other components in the travel control device 14, such as a communication circuit 14d and a laser positioning system 14h, via the general-purpose input/output port.

The configuration other than the configuration described above with respect to FIG. 19B is the same as the configuration in FIG. 19A. Therefore, a description of the common configuration will be omitted.

The AGV 10 in the embodiment of the present disclosure may include safety sensors such as an obstacle detection sensor and a bumper switch (not shown).

(4) Configuration example of operation management device



FIG. 20 shows an example of the hardware configuration of the traffic management device 50. The traffic management device 50 includes a CPU 51 , a memory 52 , a position database (position DB) 53 , a communication circuit 54 , a map database (map DB) 55 , and an image processing circuit 56 .

The CPU 51, memory 52, position DB 53, communication circuit 54, map DB 55, and image processing circuit 56 are connected by a communication bus 57, and can exchange data with each other.

The CPU 51 is a signal processing circuit (computer) that controls the operation of the traffic management device 50. Typically, the CPU 51 is a semiconductor integrated circuit.

The memory 52 is a volatile storage device that stores computer programs executed by the CPU 51. The memory 52 can also be used as a work memory when the CPU 51 performs calculations.

The position DB 53 stores position data indicating each possible destination of each AGV 10. The position data may be represented by coordinates virtually set within the factory by an administrator, for example. Location data is determined by the administrator.

The communication circuit 54 performs wired communication based on, for example, the Ethernet (registered trademark) standard. The communication circuit 54 is connected to the access point 2 (FIG. 14) by wire, and can communicate with the AGV 10 via the access point 2. Communication circuit 54 receives data to be transmitted to AGV 10 from CPU 51 via bus 57. Further, the communication circuit 54 transmits data (notification) received from the AGV 10 to the CPU 51 and/or the memory 52 via the bus 57.

The map DB 55 stores map data inside a factory or the like where the AGV 10 runs and position data of a specific area. The data format does not matter as long as the map has a one-to-one correspondence with the position of each AGV 10. For example, the map stored in the map DB 55 may be a map created by CAD.

Traffic management device 50 can determine the route of AGV 10 so that AGV 10 detours around a specific area, for example.

The position DB 53 and the map DB 55 may be constructed on a nonvolatile semiconductor memory, a magnetic recording medium such as a hard disk, or an optical recording medium such as an optical disk.

The image processing circuit 56 is a circuit that generates video data displayed on the monitor 58. The image processing circuit 56 operates exclusively when the administrator operates the operation management device 50. In this embodiment, further detailed explanation will be omitted. Note that the monitor 58 may be integrated with the traffic management device 50. Further, the CPU 51 may perform the processing of the image processing circuit 56.

The general aspects described above may be implemented by a system, method, integrated circuit, computer program, or storage medium. Alternatively, it may be realized by any combination of systems, devices, methods, integrated circuits, computer programs, and recording media.

The moving object of the present disclosure can be suitably used for moving and transporting things such as luggage, parts, and finished products in factories, warehouses, construction sites, logistics, hospitals, and the like.

DESCRIPTION OF SYMBOLS 1... User, 2a, 2b... Access point, 10... AGV (mobile object), 11a, 11b... Drive wheel (wheel), 11c, 11d, 11e, 11f... Caster, 12 . . . Frame, 13 . . . Transport table, 14 . . . Travel control device, 14a . Position estimation device, 16a, 16b...Motor, 17a, 17b...Motor drive circuit, 20...Terminal device (mobile computer such as a tablet computer), 50...Operation management device, 51...CPU , 52... Memory, 53... Location database (position DB), 54... Communication circuit, 55... Map database (map DB), 56... Image processing circuit, 100... Mobile object Management system, 102... Laser range finder, 104... Storage device, 106... Signal processing circuit, 300... Map creation system

Claims (12)

A map creation system that creates a map that a mobile object refers to in order to estimate its own position,



A first distance that can be measured for each angle by emitting a laser beam and acquiring reflected light while changing the angle within a first angle range, and using the relationship between the emitted laser beam and the reflected light. a laser range finder that obtains distance data indicating the distance to reflective points existing within the range;



Select one or more partial areas smaller than the measurable area from the measurable area defined by the first angular range and the first distance, and reach the reflection point included in the one or more partial areas. and a signal processing circuit that creates a map using distance data indicating the distance of



The one or more partial areas are narrower than a measurement area of a laser range finder used by the mobile body to estimate its own position.



Cartography system. The signal processing circuit selects a region defined by the first angular range and at least one second distance shorter than the first distance as the one or more partial regions.



The map creation system according to claim 1. The signal processing circuit selects a region defined by at least one second angular range smaller than the first angular range and the first distance as the one or more partial regions;



The map creation system according to claim 1. The signal processing circuit has at least one second angular range smaller than the first angular range;



After selecting one or more partial areas defined by the first distance, further select at least one third angular range other than the at least one second angular range and shorter than the first distance. selecting a region included in a third distance as the one or more partial regions;



Create a map using distance data indicating the distance to the reflection point included in the newly selected partial area,



The map creation system according to claim 3. Further comprising a storage device that stores in advance selection criteria data that associates distance with an intensity threshold regarding the intensity of reflected light,



The signal processing circuit acquires the distance data and intensity data indicating the intensity of the reflected light from the laser range finder for each angle,



obtaining the intensity threshold according to the distance using the distance data and the selection criterion data;



selecting a region including a reflection point where the intensity data is less than or equal to the intensity threshold as the one or more partial regions;



The map creation system according to claim 3 or 4. 5. The map creation system according to claim 1, further comprising an input device that receives designation of the one or more partial areas from a user. The laser range finder acquires the distance data using a relationship between a time when the laser beam is emitted and a time when the reflected light is received.



A map creation system according to any one of claims 1 to 6. The laser range finder acquires the distance data using the relationship between the phase of the emitted laser beam and the phase of the reflected light.



A map creation system according to any one of claims 1 to 6. A signal processing circuit used in a map creation system that creates a map that a mobile object refers to in order to estimate its own position, the map creation system having a laser range finder,



The laser range finder emits a laser beam while changing angles within a first angle range to obtain reflected light, and utilizes the relationship between the emitted laser beam and the reflected light to: Obtaining distance data indicating the distance to a reflection point existing within a measurable first distance,



The signal processing circuit selects one or more partial regions smaller than the measurable region from the measurable region defined by the first angular range and the first distance;



creating a map using distance data indicating a distance to a reflection point included in the one or more partial areas;



Selecting an area narrower than a measurement area of a laser range finder used when the mobile body estimates its own position as the one or more partial areas;



signal processing circuit. A moving body comprising the signal processing circuit according to claim 9, the laser range finder, and a driving device for movement. A map creation method for creating a map that a mobile object refers to in order to estimate its own position, the method comprising:



Using a laser range finder, emit a laser beam while changing the angle within a first angle range and obtain reflected light,



Utilizing the relationship between the emitted laser beam and the reflected light, obtain distance data indicating the distance to a reflection point existing within a measurable first distance for each angle,



One or more partial areas smaller than the measurable area from the measurable area defined by the first angular range and the first distance, and which are used by the moving body to estimate its own position using a laser beam. Select one or more partial areas narrower than the range finder measurement area,



creating a map using distance data indicating a distance to a reflection point included in the one or more partial areas;



Map creation method. A map creation system that creates a map that a mobile object refers to in order to estimate its own position,



A first distance that can be measured for each angle by emitting a laser beam and acquiring reflected light while changing the angle within a first angle range, and using the relationship between the emitted laser beam and the reflected light. a laser range finder that obtains distance data indicating the distance to reflective points existing within the range;



selecting one or more partial regions smaller than the measurable region from the measurable region defined by the first angular range and the first distance;



A map creation system comprising: a signal processing circuit that creates a map using distance data indicating a distance to a reflection point included in the one or more partial areas.

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